RE: [CAD_CAM_EDM_DRO] Encoder/Servo question

Hi Bill
A dividing head or rotary stage might have a lot of backlash and friction
(such as a typical worm drive rotary table) or it might have very little.
I am having to design one now for a company that has no backlash.

Backlash and stick/slip cause some difficulties with servo systems. That
is because they are non-linear. I am using the word non-linear in the
engineering sense...That means that the motions cannot be described by a
linear differential equation. It's a bit different from describing circular
motion as non-linear.

That being said... servo systems operate routinely with a good bit of
stick slip and other non-linearities. They can partially correct for some of
them,
even though phase margin (stability) might be a little lower.

Are you trying to build a servo driven rotary axis?


Les

Leslie M.Watts
L M Watts Furniture
Tiger Georgia

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-----Original Message-----
From: Bill Vance [mailto:ccq@...]
Sent: Friday, July 16, 2004 5:43 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Encoder/Servo question


Ok, I think I've got all the responces figured out, but what about
non-linear
applications, say for a rotary table or dividing head? Would that much
flexion,
friction, and backlash, etc,. still be present? I can see some, but wouldn't
there be significantly less of it?

Bill